Reaction Dynamics of Excited States of Transition Metal Atoms

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The dynamics of the excited states has been studied experimentally for the reactions involving gas-phase metal atoms. Based on the experimental results, the detail information about potential energy surfaces has been obtained. The crossed-beam technique has been used to achieve the single collision condition, which avoids collisional mixing of electronic states prepared.Metal atoms were generated by the laser vaporization and issued as a metal atomic beam. This beam was crossed with a molecular beam at right angle and reaction products in the crossing region were detected by laser-induced fluorescence (LIF) and/or chemiluminescence techniques. During the term of this project, the following reactions have been studied.Al(^2P_<1/2,3/2>)+O_2(S^3Σ^-_g)→AlO(X^2Σ^+)+O(^3P_J) (1)Y(^2D_<3/2,5/2>)+O_2(X^3Σ^-_g)→YO(X^2Σ^+,A^2Δ_<3/2,5/2>,A^2Π_<1/2,3/2>)+O(^3P_J) (2)Two spin-orbit states were selectively generated and vib-rotational state distributions of AlO were determined for these initial staets. The vacuum ultraviolet LIF technique was employed to determine the populations of three spin-orbit states of the O atom. For both spin-orbit states of Al, the vib-rotational states show almost statistical distribution. This result suggests that the reaction proceeds via a long-lived intermediate. On the other hand, the spin-orbit states of O do not agree with the statistical expectation. This interaction among different spin-orbit states likely to occur at entrance and exit channels of the intermidiate.Chemiluminescence spectra of YO(A^2Π_<1/2,3/2>) were analyzed to determine the energy partition into this product. The vib-rotational state distributions are again almost statistical and a complex mechanism is suggested. The Doppler profiles of the O atom were analyzed to estimate relative branching ratios for YO in the ground state vs. YO in the excited states. The results suggest that more than two pathways take place in reaction (2).